The present invention relates to a connector for use in a mobile phone or cellular phone, notebook personal computer, digital camera or the like, and more particularly to a connector capable of reliably urging contacts against a flexible printed circuit board or flexible flat cable, facilitating conducting the circuit board or flat cable into the connector and at the same time achieving miniaturization of the connector, eliminating any defective connection even if the circuit board is inserted into the connector erroneously upside down, reliably locking the board or cable to the connector, miniaturizing the connector even in the case of the circuit board having contacts on both surfaces, and reinforcing the connector preparatory to mounting it onto the board or cable.
In general, connectors for use in mobile phones, charge coupled device (CCD) cameras and the like are much thinner (so-called lighter and more compact connectors) and include contacts arranged in extremely narrow pitches. These connectors are used with both the flexible printed circuit boards and flexible flat cables or used exclusively to flexible printed circuit boards. These connectors have a construction that by inserting a circuit board or flat cable into an insertion opening of its housing, the circuit board or flat cable is brought into contact with contact portions of the contacts.
These connectors are roughly classified into two kinds. The connectors of one kind mainly comprise a housing and contacts, and when a flexible printed circuit board is inserted into the housing, it is brought into contact with contact portions of the contacts. This type of connectors is so-called “non-zero-insertion force” (NZIF) type. The connectors of the other kind mainly comprise a housing, contacts and a slider so that a flexible printed circuit board is embraced by the housing and the slider. The connectors of this type are further divided into two kinds, that is, so-called “zero-insertion force” (ZIF) type and “piano touch” type. There are various methods for holding the flexible printed circuit board by the housing and the slider. In many cases, however, after a flexible printed circuit board has been inserted into the housing, the slider is inserted into the housing to urge the circuit board against contacts. The “zero-insertion force” type is disclosed in the patent literature 1, and the “piano touch” type is in the patent literature 2 described below.
The connector of “non-zero-insertion force” type has a construction in that a flexible printed circuit board is inserted through the insertion opening into the housing to force the board into contact with contact portions of the contacts without using a slider, thereby accomplishing the connection of the circuit board. The flexible printed circuit board is subjected to pressure when being inserted into the housing. When the flexible printed circuit board is caused to contact the contact portions, the contact portions are sometimes intentionally curved or bent in order to facilitate their contacting, or the contact portions of the contacts are often provided in symmetry across the board to embrace it by the contact portions.
The housing is formed with a required number of insertion grooves for inserting the contacts therein and an insertion opening for inserting the flexible printed circuit board. The contacts each mainly comprise a contact portion adapted to contact a flexible printed circuit board or the like, a connection portion to be connected to a board, and a fixed portion to be fixed to the housing. These contacts are fixed to the housing as by press-fitting. FIGS. 30A and 30B illustrate a contact 64 of the “zero-insertion force” type connector. This contact 64 is substantially in the form of a U-shape and mainly composed of a contact portion 22 adapted to contact a flexible printed circuit board 40 or flexible flat cable, a connection portion 24 to be connected to a board or substrate, and a fixed portion 42 to be fixed to the housing 62 as by press-fitting.
As shown in FIGS. 30A and 30B, a slider 66 of the “zero-insertion force” type is substantially in the form of a wedge. The slider 66 is inserted into the housing 62 having the required number of the contacts 64 arranged therein, after the flexible printed circuit board 40 or flexible flat cable has been inserted into the housing 62. Such a slider 66 mainly comprises a mounting portion 74 to be mounted on the housing 62, and an urging portion 68 for urging the flexible printed circuit board 40 or flexible flat cable against the contact portions 22 of the contacts 64. Prior to the insertion of the flexible printed circuit board 40 or flexible flat cable, the slider 66 is temporarily inserted in the housing 62 for the purpose of storage as shown in FIG. 30A. After the circuit board 40 or cable has been inserted, the slider 66 is again inserted into the housing 62 so that the urging portion 68 of the slider 66 is inserted in the direction in parallel with the circuit board 40 or cable as shown in FIG. 30B, whereby the board 40 or cable is urged against the contact portions 22 of the contacts 64.
In order to accommodate a customer's specification, minimize pitches of contacts, or miniaturize a connector, it is sometimes required to arrange connection portions of contacts on the side of the insertion opening of the housing (or to arrange the contacts alternately staggered).
Moreover, the patent literature 3 described below discloses a construction for locking a flexible printed circuit board. The patent literature 4 discloses a connector for a circuit board with a view to improving productivity by reliable connection without positional shifting of circuit board even if the circuit board has particularly miniaturized terminals or terminals arranged in minimum pitches for signal inputs and outputs.
Patent Literature 1
Japanese Utility Model Application Opened No. H6-60,983 discloses one example of connectors of the “zero-insertion force” type. As can be seen from the “Abstract” of the Japanese Utility Model, this invention relates to a connector with a slider for a print board for use in a narrow space in an electronic or communication appliance. The slider is formed at ends on both sides with U-shaped arms with their proximal ends fixed to the slider as guiding means when being inserted into a housing. The U-shaped arms are each provided on its opening side with a projection and formed with a notch such that the opening end is visible from the inserting side. The housing is provided at both the ends with projections having an oblique surface adapted to engage the projection of the slider.
When the slider together with connection terminals of a flexible printed circuit board is inserted into the housing, the projections of the slider ride over the projections having the oblique surface of the housing so that the opening ends of the U-shaped arms of the slider are temporarily spread outwardly and then returned to their normal positions when the insertion has been completed.
Patent Literature 2
Japanese Patent Application Opened No. H13-257,020 discloses one example of the so-called “piano touch” type connector. With a view to obtaining an accurate positioning of a flexible printed circuit board relative to contacts of the disclosed connector, projections are provided in a row on a line on a terminal block between the contacts. After a flexible printed circuit board or flat cable has been inserted into the terminal block, a slider is moved to urge the circuit board or flat cable against the contacts. At the moment when the circuit board or flat cable is electrically connected to the contacts by the slider in this manner, the projections snap into recesses between patterns of the circuit board or flat cable, thereby ensuring positional coincidence between the contacts and patterns of the circuit board or flat cable.
Patent Literature 3
Japanese Utility Model Application Opened No. H6-82,783 discloses a construction of a connector for locking a flexible flat cable. With a view to causing a flat cable to easily engage jaws of a slider even if the flat cable having on its rear surface a rigid reinforcing plate, the disclosed connector includes a housing provided therein contact pins and forming fitting space therein for receiving a flat cable, and a slider removably provided in the space of housing and pivotally movable out of the housing when the slider is removed therefrom. After the flat cable has been inserted into the fitting space in the housing, the slider is forced into the fitting space to cause the flat cable to be electrically connected to the contact pins. The slider is provided with anchoring projections on its surface against which the flat cable abuts. The anchoring projections of the slider are inserted in and engaged with anchoring portions formed in the flexible flat cable and a reinforcing plate provided on its rear surface.
Patent Literature 4
Japanese Patent Application Opened No. H5-326,084 discloses a connector for a circuit board. According to the description in the “Abstract” of the Japanese Patent, the connector accomplishes reliable connection to improve productivity without any positional shifting even if the circuit board having signal input-output terminals arranged with minimum pitches and the terminals themselves being miniaturized. A circuit board includes a plurality of signal input-output terminals arranged in rows at an edge of the circuit board. The connector includes jack terminal contacts arranged at corresponding locations to the signal input-output terminals of the circuit board. After the circuit board has been inserted through an opening on the side of the terminal contacts into the connector, the circuit board is urged and moved toward the contacts of the jack terminals so that the signal input-output terminals are brought into contact with the corresponding contacts of the connector. The connector further comprises positioning means arranged in the region where the insulator circuit board is inserted. When the circuit board is inserted into a predetermined position, the positioning means will position the circuit board thereat.
In recent years, with miniaturization of electrical and electronic appliances, the connectors of this kinds have been strongly required to be more miniaturized. Recently, moreover, there has been increasingly a need for connectors having a small number of connection lines such as 4 to 10 depending upon customer's specifications. On the other hand, it is better to be able to insert a circuit board into a connector with a slight force, while it is better to be able to hold the circuit board in the connector with a sufficiently strong force. The insertion and holding forces are incompatible with each other in this manner and therefore give rise to the following problems.
First, in the connector of the prior art shown in FIGS. 30A and 30B, there are six layers in height, that is, the upper and lower walls of the housing 62, the contact portion 22 and the pressure receiving portion 70 of each of the contacts 64, the urging portion 68 of the slider 66 and the flexible printed circuit board 40 or flexible flat cable. In order to reduce the connector's height as much as possible, it is possible to omit the pressure receiving portion 70 of each of the contacts to obtain five layers in height. It is however impossible to more reduce the height of the connector in consideration of strength of the respective members and specifications or customer's demands.
With the connector 60 shown in FIGS. 30A and 30B, the insertion of the circuit board 40 or flat cable and urging of the contact portions 22 of the contacts 64 against the circuit board or flat cable take place only on the side of the insertion opening of the housing, so that as the connector is miniaturized, such operations would become more difficult. In the case that extremely narrow pitches of contacts are required, moreover, the insertion of contacts into a connector from only one direction would prevent or impede the required miniaturization of the connector.
Second, with the connector described above, in the case that the contacts are arranged in the housing in a manner that their connection portions are located on the side of the insertion opening of the housing, it is unavoidable that the connection portions of the contacts extend from the housing in order to facilitate the induction of a circuit board or flat cable so that the extension of the connection portions from the housing would limit the miniaturization of the connector. In the case that extremely narrow pitches of contacts are required, the insertion of the contacts into the housing from only one side would also limit the miniaturization of the connector.
Third, in a connector having contacts whose contact portions are provided in symmetrical positions in order to embrace a flexible printed circuit board on both its sides, the contacts are often arranged alternately staggered for the purpose of miniaturizing the connector. In this case, patterns on the circuit board to be inserted into the connector should be arranged alternately staggered corresponding to the arrangement of the contacts of the connector. If the circuit board is inserted into the connector erroneously upside down, the patterns on the circuit board are improperly brought into contact with the contact portions of the contacts, resulting in defective or failed electrical connection. If such a defective or failed connection occurred, the connector itself or the circuit board itself would need to be replaced, resulting in an increased operating cost.
Fourth, in the so-called “non-zero insertion force” type connector, the force for inserting a circuit board into the connector and the force for holding the circuit board in the connector are generally determined substantially depending upon the contacting force (or pressure) of the contacts. In other words, the holding force is substantially equal to the contacting force per one contact multiplied by the number of contacts. If a customer demands a holding force of 5 N, it is impossible for a connector having connection lines whose number is less than 10 to obtain the holding force of 5 N. Therefore, the circuit board is slipped out of the connector to cause failed connections.
Even in the so-called “zero-insertion force” type connector, in which after a flexible printed circuit board has been inserted into the connector, the circuit board is urged against the contacts by the slider, although it is different from the “non-zero-insertion force” type connector only in the fact that initial value is increased by inserting the slider into the connector, the influence of the contacting force (pressure) of contacts is still great, and therefore the same holds true in case of the connector of this type in that it is impossible for the connector having connection lines less than 10 to obtain the holding force of 5 N so that the circuit board will be slipped out of the connector.
In the connector disclosed in the Patent Literature 3 described above, the anchoring projections provided on the slider are inserted in and engaged with anchoring portions of the flexible cable. In such a connector, however, as the direction in which the slider is inserted is the same as the direction in which the flexible cable is inserted, the influence of the contacting force (pressure) of contacts is still great, and therefore the same holds true in this case so that with connection lines less than 10, the flexible cable will be slipped out of the connector.
In the combination of connectors disclosed in the Patent Literatures 2 and 3, the connector of so-called “piano touch” type in Literature 2 is further provided with anchoring projections formed in the slider and anchoring portions formed in the circuit board as the connector in Literature 3. With such a combination type connector, a required holding force can be obtained to some extent even if the connection lines are less than 10, because the direction in which the circuit board is inserted is different from the rotating direction of the slider. However, the slider's elasticity is poor, so that the slider or circuit board would be damaged when the circuit board is pulled by a force more than the holding force. Moreover, when the circuit board is accidentally subjected to an irregular force, such a force is usually a tension directed in obliquely upward direction, but not in the direction opposite to the inserting direction. Therefore, as the direction of the accidental irregular force is the same as the rotating direction of the slider, sometimes the required holding force cannot be obtained.
Fifth, in order to increase signal density, providing contact portions on both surfaces of a circuit board is increasingly being required. However, the connectors of the prior art described above could not accommodate such circuit boards having contact portions on both the surfaces and further could not accommodate much narrower pitches of contacts. In more detail, with the “zero-insertion force” type connector as disclosed in the Patent Literature 1, after the circuit board has been inserted into the connector, the circuit board is urged in one direction by means of the slider so as to contact the contacts of the connector. As the urging direction is only one direction, it is quite impossible to use this connector with a circuit board having contact portions on both the surfaces.
In the “piano touch” type connector disclosed in the Patent Literature 2 described above, the slider is pivotally moved on the side where the circuit board is inserted into the connector. In this construction, the circuit board is urged only in one direction by the slider so that this connector could not accommodate a circuit board having contact portions on both the surfaces.
Sixth, the height or thickness of connectors is increasingly being reduced so that nowadays a thickness of as little as 0.15 to 0.25 mm is pursued. With such an extremely thin housing, on inserting a circuit board into the connector, the housing could not withstand the contacting force so that the housing is deformed causing unstable connection leading to defective or failed connection and in a worse case causing damage to the housing. Making the housing thicker may avoid such a damage, but it could not accomplish the reduction in height. The connectors disclosed in the Patent Literatures 1 and 2 have the contacts arranged in narrower pitches and are much thinner (so-called lighter and more compact) so that aforementioned problems are particularly acute in these connectors.